Solvation and depolymerization of coal



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UNITED STATES PATENT- OFFICE sows-non or r V rchin, United States ofAmerica as represented Pa While thesecretaryofthelntcrior No Drawing.Appli Serial N cation July 187,

Claims. (01. 10614) (Granted under the act of amended April 8., 1m;

The invention herein described and claimed may be manufactured and usedby'or for the Government of the United States of America forgovernmental purposes without the payment of any royalties thereon ortherefor.

This invention relates to the conversion of solid carbonaceousmaterials, such as bituminous and subbituminous coals, lignites, peatand the like, to liquid products of enhanced value and utility. Whensuch materials are treated in accordance with the invention the primaryproducts are extracts containing little or no ash and which are suitablefor direct use as. fuels or for use as raw materials for the productionof industrial products such as carbon black. Such extracts of low ashcontent likewise may be used in hydrogenation processes for theproduction of synthetic liquid fuels corresponding to gasoline,kerosene, Diesel fuels and the like from petroleum sources.

Because of the highly aromatic character of the hydrogenation products01' such extracts this process provides a means for greatly increasingthe potential supply of benzene, toluene and related compounds.

It is an object of my invention to secure the solution of solidcarbonizable fuels under the mildest possible conditions wherebysecondary reactions will be minimized. A further object of the inventionis the improvement of hydrogenation of coal and the like as an extractutilizing for the vehicle selected liquid fractions produced by thehydrogenation of such extracts. Other objects will be apparent from thefollowing description.

A number of processes are known for the extraction of solidpyrobituminous materials such as coal, lignite, peat and the like. Ingeneral, all of these processes involve the use as the treating vehicleof mixtures comprising phenols and tetrahydronaphthalene as described,for example, in Pott and Broche Patent 2,147,753 and Pier and DonathPatent 2,215,190. In these prior art methods the ratio of hydrocarbon tophenols in the solvent mixture is customarily about 4:1.

I have found that greatly improved yields of soluble materials can besecured by the use as the solvent vehicle of dicyclic hydro-aromaticcompounds containing a phenolic hydroxyl group. Examples of suchcompounds which are particularly efiective are orthoandpara-cyclohexylphenol and tetrahydronaphthols, such as 1,23,4-tetrahydro-5-hydroxynaphthalene.

These solvents normally are employed in about equal parts by weight withthe solid carbonizable fuel being extracted, that is a ratio of from 1:1to

March 1, 1883, a 37. O- G. 78'" 3:2. Under some conditions of operationshowever the amount of solvent may be increased. al- 1 though in generalit is not necessary or desirable to exceed a ratio of about 4:1.

The extraction is'carried out using finely ground or comminuted coal,limits and the like with the solvent in the desired ratio, underpressures of about 500 pounds per square inch and at temperatures orabout 400 C. while the pressure may be higher or lower than 500 poundsper square inch, normally it should not exceed about 1500 pounds persquare inch. Temperatures may vary from about 250 C. to as high as 4500., although for typical American bituminous coals it is preferred tooperate at approximately 400 C. The operating temperature, in any event,should not exceed that at which there is noticeable pyrolysis of thecoal, etc., to be extracted.

This process may be carried out as a batch type operation or incontinuous or semicontinuous manner as desired. Either a neutral orreducing atmosphere may be maintained during the extraction. Under mypreferred conditions there is no substantial hydrogenation of theextract, the consumption of hydrogen representing from 1-2% by weight orthe solid material being extracted.

It is not necessary to use substantially pure compounds in this class.Quite satisfactory results may be secured from crude compounds andmixtures, of course, will give equally desirable results. Thus, mixturesof orthoand paracyclohexylphenol are suitable for the process, as aremixtures of the tetrahydrohydroxynaphthalenes. The high boiling tar acidfractions from the hydrogenation of certain coals aflord a suitablesource from which may be conveniently prepared crude mixtures of thesenovel solvents which may be used without further separation and/orpurification.

Following the pressure extraction, the solid residual matter isseparated from the extract by filtration or centrifuging. The separatedsolids consist for the most part of the mineral matter, or ash, of thecoal or thelike starting material, together with unconverted orunextracted starting material. The separation may be effected with orwithout dilution with the same or other solvents. Such diluents,vhowever, should be chemically similar to the initial solvents,preferably containing a phenolic hydroxyl group in the molecule, as Ihave found that benzene and similar non-polar aromatic compounds arelikely to precipitate some of the extracted material. Such precipitates,particularly when admixed Example I A Bruceton bituminous coal fromthePittsburgh bed was ground to pass 90% through a 100 mesh screen. Thiscoal had the following analysis:

' Percent Proximate analysis: by weight Moisture V 2.1 Volatile matter36.0 Fixed carbon 54.! Ash v 7.2

Ultimate analysis:

Hydrogen 5.2 Carbon 75.5 Nitrogen 1 1.5 Sulfur 1.5 Oxygen 9.1 Ash 7.2

One part of the ground coal was admixed with four parts by weight ofo-cyclohexylphenol and charged to a stainless steel autoclave containinghydrogen at one atmospheric pressure. The sealed vessel and contentswere heated to 400 C. while being rotated to agitate the contents.- Thepressure, due to the vapors of the solvent and any permanent gasespresent, rose to about 500 pounds per square inch. After thirty minutesof treatment the contents of the autoclave were discharged andcentrifuged to separate extract from the mineral residue (ash) andunconverted coal constituents. The percentage of extraction wasdetermined as 81.6 calculated according to the following formula:

percentage extraction 100 weight of weight of dry, ash-free coal Whenthe same coal is extracted under comiparable conditions with a solventcomprising naphthalene, phenol and tetralin (2:1:2) the percentage ofextraction was 51.3, while with tetralin alone the percentage was 49.4.

Example II The autoclave was charged with asample of the same coal usedin Example I, admixed with o-cyclohexylphenol in the same proportion,but

the treatment was continued for one hour.

There was a slight increase in the yield'of extracted material, thepercentage of extraction calculated as in Example I being 82.8.Substantially the same yield was also obtained upon an increase in timeto ninety minutes.

Example III The autoclave was charged with a mixture of residue(100percent ash in residue).

1,2,3,4-tetrahydro 5 hydroxynaphthalene and the Bruceton coal used inExample I, in the ratio 4:1 and heated to 400 C. for 30 minutes under aninitial hydrogen pressure of 1 atmosphere. The extraction products wereseparated by cen- 4 I extract, the latter may betreated by distillationv or any other conventional .process for recovery various ways notforming part of the present invention. 1 v

The solutions obtained according to this'invention are quite stable. Asample of the extract in o-cyclohexylphenol was exposed to air at 45 C.for'nineteen days withoutsignificant change in appearance or properties.The expressions solution, "extract and the like'used herein are intendedto describe the liquid product from no material can be separated byfurther filtration or centrifuging. Microscopic examination at 400magnification indicates substantial absence of solid particles. It ispossible, however, that there is actually a form of colloidal dispersionrather than; true solution. Accordingly 7 it will be understood. that myinvention is notv intended to be limited to any particular theory as tothe mechanism of the action whereby a substantial proportion of the coalsubstance is extracted in soluble form.

According to the patent statutes, I- have set forth the principles andmode of operation of my invention and have described whatv I believe torepresent its best embodiment. I desire it to' be understood, however,that within the scope 'of the appended claimsv the invention may bepracticed otherwise than as specifically described herein.

I claim:

l. A process for the solvation and depolymerization of solidcarbonizable fuel for the production of extracts therefrom whichcomprises treating said fuel with at least an equal weightof a liquiddicyclic hydroaromatic compound containing at least one phenolichydroxyl group in an'atmosphere rich in hydrogen at a temperature offrom about300 C. to about 415 C. and at a pressure corresponding to thevapor pressure of said compound at said temperature and thereafterseparating the resulting extract from solidv residues;

2. Ina process for the preparation of liquid products from solidcarbonizable fuel. the improvement which comprises treating the fuelwith a liquid dicyclic hydroaromatic compound containing at least onephenolic hydroxyl group in the presence of hydrogen at superatmosphericpressures and at elevated temperatures not in excess of those at whichpyrolytic conversion of the fuel will occur.

3. A process for the production of extracts of coals lignite, peat andthe like solid fuel comprisingcomminuting said fuel, admixing therewitha liquid'dicyclic hydroaromatic compound containing at least onephenolic hydroxyl group, heating said mixture to a temperature of about400 C. in an atmosphere of hydrogen under a pressure corresponding tothe vapor pressure of said imuid at said temperature and thereafterseparating the extract from the insoluble residue of said fuel atreduced temperatures and pressures.

bituminous coal which comprises treating said coal with at least anequal weight of a solvent composed essentially of ortho-cyclohexylphenolin an atmosphere of hydrogen at a temperature trifuging as describedabove.- The yield was of about 400 C. and under a pressure notin excessof about 1500 pounds per square inch, separating the resulting extractfrom ash and other solid residues at substantially reduced pressures 8and temperatures, recovering at least a major portion or the solventfrom said extract and returning recovered solvent to the process fortreatment of further quantities of coal therein.

5. A process for the production of extracts from bituminous coal whichcomprises treating said coal with at least an equal weight of a solventcomposed essentially of para-cyclohexylphenol in an atmosphere ofhydrogen at a temperature of about 400 C. and under a pressure not inexcess of about 1500 pounds per square inch, separating the resultingextract from ash and other solid residues at substantiallyreducedtemperatures and pressures, recovering at least a major portionof the solvent from said extract and returning recovered solvent to theprocess for treatment offurther quantities of coal therein.

6; A process for the production of extracts from bituminous coal which.comprises treating said coal withat least an equal weight or a solventcomposed essentially of 1,2,3,4-tetrahydro-5-hydroxynaphthalene in thepresence or hydrogen at a temperature or about 400 C. and under apressure not in excess of about 1500 pounds per square inch,and'separatlng the resulting extract from ash and other solid residuesat substantially reduced temperatures and pressures.

- MILTON ORCHIN.

REFERENCES crrnn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS OTHER-REFERENCES Bull. soc. -chim.vBelg., vol. 43,pages 382-391 (1934) by Gillet et 81., abstracted in Chem. A bstracts29, page 16087.

Ellis, "Hydrogenation oi Organic Submnces." 3rd edition. page 236.published Nov.'1930, Van

- Nostrand & 00., New York.

